We extended the work described in last year's progress report by attempting to find improved predictors of arousal from an array of variables derived from non-EEG-related measurements. We examined various other respiratory-based measures for correlation to arousal. The following were calculated on an epoch-to-epoch basis and compared to the visually-scored arousal index: (1) the average value of the fuzzy-based severity index, SI; (2) the standard deviation of SI; (3) average inspired tidal volume; (4) standard deviation of tidal volume; (5) the maximum breath-to-breath change in inspiratory peak flow; and (6) the ratio of the maximum tidal volume over the minimum tidal volume. These variables were computed from our database of 13 patients with sleep-disordered breathing. The respiratory-based variable with the highest sensitivity of predicting arousal (75%) was the standard deviation of SI. The respiratory-based variable with the highest specificity in predicting arousal was the standard deviation of tidal volume (81%). However, the sensitivity associated with this variable was only 68%. Thus, the respiratory-related measure with best overall scores in both sensitivity and specificity was the standard deviation of SI.